Replacing Components In Tascam M-320

[spacecommandant]

The headphone output on my mixer has died and, since I'm making a Mouser order anyways, I thought I would take the opportunity to replace the headphone amp caps, IC, and transistors shown in the schematic (pages 149 & 150 in the manual), which will hopefully take care of the issue. Unfortunately, the diodes are difficult to make out in the drawing.

Q007 & Q008 are 2SC1815, which Mouser carries.
Q009 & Q010 are 2SA1015; Mouser has KSA1015YTA, which looks like a match.

What I need to find replacements for are Q11 & Q12 (2SC2877) and Q13 & Q14 (2SA1217).
Any suitable replacements that you know of?

Thanks in advance..

 

[fixorfling]

Set your multi-meter to Diode test,
check the Diodes and Transistors and IC OpAmp 1/2,
then the Voltage rails and caps resistors ect, on the appropriate setting,
Try and find the actual fault first.

Blanket replacement, of the components, is like shooting in the dark.
Stick with the original components, as equivalents may not work, regarding bias/Hfe.

Or you may end up, removing the equivalents parts you've fitted,
putting the original parts back in, and it still not working correctly.

 

[heatwalk]

What above said. Do you have a scope? Shotgunning everything is rarely necessary and sometimes something may have happened elsewhere. I recently worked on a 388 that had transport issues and replacing everything in sight wouldnt have solved anything since it ended up being a physical problem. Are both left and right channels out? I would check input and output of op amp and measure the voltage as suggested. That to me is the first thing that would go. If the rails show they are pulled down/ short and no output you should pull it and check if the rails go back up

 

[spacecommandant]

Thanks for recommending the common sense approach. I took time to probe the components and discovered Q7 & Q8 looked a little dodgy, so I just replaced them and the headphone out is now working.
Thanks again!